The present invention relates to the use of Aspartame.TM. in an aseptically packaged fruit juices and fruit drinks. Aspartame.TM. is the trademark of an artificial sweetener comprising the dipeptide of the commercially produced amino acids, L-phenylalanine (as the methyl ester) and L-aspartic acid. It is about 200 times sweeter than sugar. Hence, relatively small quantities can be used to produce a sweet, good-tasting drink or juice which is very low in calories.
The problem with using Aspartame.TM. is aseptically packaged drinks is that the drink and all of its contents must be sterilized prior to packaging. Pasteurization is critical lest the drink ferment or otherwise deteriorate during shelf storage. Unlike soft drinks, aseptically packaged juices or fruit drinks do not have sufficient cabonation to assist in sterilization and do not contain preservatives. Hence, the aseptically packaged juice or fruit drink must be pasteurized prior to packaging.
Aspartame.TM. is very heat sensitive and tends to deteriorate during the juice pasteurization process. An Aspartame.TM. sweetened fruit juice or fruit drink which tastes sufficiently sweet prior to pasteurization loses its sweetness to a significant and noticable degree after pasteurization.
A similar phenonmenon occurs with respect to juice flavoring ingredients. Hence, prior artisans have heretofore added juice flavoring ingredients back into a pasteurized juice or juice drink after pasteurization, by passing the flavor ingredients through a purifying microfilter. One's initial thought is to do the same thing with Aspartame.TM. by dissolving it and passing the solution through a microfilter.
The problem with this approach is that Aspartame.TM. is not particularly soluble in conventional solvents. Its producer, G. D. Searle and Company, reports that it is approximately 1% soluble in water at room temperature and only 0.37% soluble in ethanol at room temperature.
G. D. Searle and Company does indicate in its literature concerning Aspartame.TM. that one can increase the solubility of Aspartame.TM. by lowering the pH of the solution with food acids, such as citric acid or malic acid. Even so, Searle reports that only about 9 grams of Aspartame.TM. are soluble in 100 milliliters of water at a pH of 2.2 at room temperature. Searle reports that a pH of 2.2 offers maximum solubility. Because of this low solubility, one tends to dilute the strength of one's fruit juice or drink by reason of the Aspartame.TM. addition. Also, the addition time is increased since more solution has to be added than would be the case if Aspartame.TM. were more soluble in water.
U.K. Pat. No. 2,103,917 published Mar. 2, 1983 to PepsiCo Inc. discloses that more concentrated Aspartame.TM. solutions can be obtained by lowering the pH of the solution to from about 1.5 to 2.2, preferably 1.7 to 2.0, with phosphoric acid. The problem with this approach is that with pHs below about 2.2, and especially below 2.0, you begin to hydrolyze and destroy the Aspartame.TM..
The United Kingdom patent also suggests, without showing examples, that fumaric, malic and citric acids will also work. However, fumaric is highly insoluble and won't work in accordance with the examples shown in the patent. Malic and citric acids won't lower the pH much below about 2.2 and do not work when used in accordance with the examples of this patent.
I have invented a process for aseptically adding flavor ingredients to fruit juices and fruit drinks after pasteurization, without having to use a microfilter, by dissolving the flavor ingredient in a high percentage alcohol solution. Unfortunately, Aspartame.TM. is even less soluble in ethyl alcohol, as noted above, and pH adjustments are not particularly meaningful in alcohol solutions.
As a result, there are serious road blocks to the use of Aspartame.TM. in aseptically packaged drinks and juices. To my knowledge, Aspartame.TM. has not heretofore achieved commercial usage for this purpose.